New liquid nitrogen spray could help NASA solve its lunar dust problem

"Moondust is electrostatically charged, abrasive and gets everywhere, making it a very difficult substance to deal with," Ian Wells, first author of a paper on the topic and a senior in WSU’s School of Mechanical and Materials Engineering, explained in the statement. "You end up with a fine layer of dust as a minimum just covering everything."

The team of Washington State University (WSU) researchers, who published a paper in the journal Acta Astronautica, explained that their liquid nitrogen spray removed more than 98 percent of moon dust simulant in a vacuum environment while causing minimal damage to spacesuits.

They also pointed out that their new method performed better than any other that had been investigated previously.

New liquid nitrogen spray efficiently cleans lunar dust

With NASA aiming to land the first woman and first person of color on the moon in 2025 with its Artemis III moon mission, it will need new solutions to problems that could affect its crew. During the Apollo missions, astronauts used brushes to try to remove lunar dust from their suits, though the method did not work very well.

Astronauts also experienced "lunar hay fever" during these missions caused by the lunar dust. Future Artemis missions will aim to explore a new region of the moon, the lunar south pole, and for much longer periods. In 2020, this issue prompted the space agency to make a call to universities for new solutions to the lunar dust problem with its Breakthrough, Innovative, and Game-changing (BIG) Idea Challenge.

The WSU researchers believe their spray, which makes use of the Leidenfrost Effect, could provide the solution. This effect can be seen when cold water is poured on a hot frying pan and it beads up and moves around on the pan's surface. When very cold liquid nitrogen is sprayed at a warmer dust-covered spacesuit, those dust particles bead up and float away with the nitrogen vapor.

The team tested their method in a vacuum to approximate the conditions on the moon and they found that it worked with 98 percent efficiency. The team took a top prize in the BIG Idea Challenge last year and they will continue to improve their solution in the coming months and years.

Study abstract:

Lunar regolith degrades human health and equipment making mitigation paramount for lunar missions. Cryogenic liquid sprays are a recently developed, simple, and convenient concept for dust mitigation in a lunar environment. However, removal efficacy and material degradation under the extreme cryogenic vacuum environment are unknown. Traditional space suit dust mitigation technologies used on the Apollo missions, such as brushing and vacuuming, introduced suit fabric abrasion which must be addressed for all dust mitigation methods considered for lunar implementation. This publication reports the efficacy of dust removal in a simulated airlock vacuum environment and the associated impact of repeated dusting-washing cycles on spacesuit materials. Specimens were impinged with measured liquid nitrogen sprays at different spray angles within a vacuum chamber. Mean mass removal of 98.4% was achieved in a vacuum environment at optimal conditions, correlating to 95.9% removal of particles below 10 μm. To investigate material degradation, a total of 26 samples were cycled a cumulative 233 times through cryogen spray washings under ambient conditions. A degradation scale was created to classify optical microscopy observations. Degradation results indicate minimal spacesuit material abrasion from liquid nitrogen removal. Results additionally show an average of 2.66% increased removal with each subsequent washing cycle for fabric washed twice, possibly due to clogging and occupancy of specific sites. The conclusion is that liquid nitrogen sprays cause relatively less damage than conventional dust mitigation techniques, even under the extremes of cryogenic temperatures and vacuum.